Protect PDF with a Password
Encrypt a PDF so it can only be opened with a password. AES-256 is used by default, and you can choose whether printing, copying and editing are allowed.
PDF Tools
11
Merge, edit, protect and more
File Limit
200 MB
Up to 2,000 pages
Processing Mode
In your browser
No server processing
Privacy Status
No uploads
Files stay on your device
Drop your file here
or click to browse
One PDF up to 200 MB. Processed on your device.
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US Salary CalculatorHow to use it
- Choose a PDF.
- Enter a password twice. Use a long passphrase that you have not used elsewhere.
- Choose the permissions to allow and, if needed, the AES-128 option for very old PDF readers.
- Select Protect PDF and download the encrypted file. Keep the password somewhere safe — it cannot be recovered.
Limits and known limitations
- Encryption uses the open-source pdf-lib library’s implementation of the PDF standard security handler (AES-256, revision 6).
- Permission settings are honoured by most readers but are not a strong security control; anyone who can open the file may be able to use software that ignores them.
- Encryption does not hide the number of pages or file size.
- A strong password matters: PDF encryption can be attacked offline by guessing passwords.
Frequently asked questions
What happens if I forget the password?
The file cannot be opened. We never see or store your password, so we cannot recover it.
Which readers can open AES-256 PDFs?
Adobe Acrobat and Reader (version 9 and later), Apple Preview, Chrome, Edge, Firefox and most modern readers. Choose AES-128 only for very old software.